JPH11309981A - Capped type mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a cap from swinging in the lateral direction when a lead is discharged by a method wherein the front end of the cap is formed in a manner to be extended to a part where the rear part of a barrel cylinder is covered when the cap is fitted on a lead tank. SOLUTION: The front side of a cap is formed to be extended in a manner to cover the rear part of a barrel cylinder 1. The inner diameter of the cap 3 at the covering part is made approx. the same as the outer diameter of the barrel cylinder 1, but a slight gap is provided because they slide with each other. In addition, the inner diameter of the rear part of the cap 3 is made approx. the same as the outer diameter of a knocking cap 20, but it is set in such a manner that a forced-in state may not be presented. Thus, by forming the front part of the cap 3 which is fitted on the knocking cap 20 in a manner to be extended to the rear part of the barrel cylinder 1, and making the rear inner diameter of the cap 3 approx. the same as the rear outer diameter of the knocking cap 20, a swinging of the cap 3 when the cap 3 is pressed, can be prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical pencil having a lead tank projecting from the rear end of a barrel.

[0002]

2. Description of the Related Art As an example, there is Japanese Utility Model Publication No. 4-25355. This is a mechanical pencil having detachable caps at the front and rear of the barrel. More specifically, when a cap is mounted on the front of the barrel, the large-diameter fitting portion (first engagement surfaces 81A to 81D) on the inner surface of the cap fits on the front outer peripheral surface of the barrel, and When the cap is attached to the rear of the barrel, the small-diameter fitting portion (the second engaging surface 9) on the inner surface of the cap is used.
1A to 91D) are fitted to the rear outer peripheral surface of the shaft cylinder.

[0003]

However, in the method of fitting a cap as shown in the prior art, when the cap is mounted behind the shaft cylinder, it is fitted only at four small diameter portions. The fitting was unstable. Especially,
When the core is extended, an excessive pressing action is applied to the cap, so that the cap swings in the left-right direction, resulting in an uncomfortable pressing operation.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is a mechanical pencil in which a lead tank is projected from a rear end of a barrel. A detachable cap is provided at the front of the barrel and at the back of the core tank, and the cap is formed to extend to a position where the front end of the cap covers the rear part of the barrel when the cap is attached to the core tank. It is the gist of what has been done.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first example will be described with reference to FIGS. Shaft barrel 1
The wick tank 2 is movably arranged inside the
The barrel 1 and the core tank 2 are formed from a transparent or colored translucent material. A circumferential fitting recess 5 that fits with a plurality of inner ribs 4 formed partially on the cap 3 is formed on a front outer periphery of the barrel 1, and a rear portion of the fitting recess 5 is formed at a rear portion of the fitting recess 5. A plurality of ring-shaped projections 6 are formed. The projection 6a located at the forefront end of the plurality of projections 6 is higher in height than the other projections. The cap 3 is fitted in the fitting recess 5 and
By causing the circumferential projection 6a to abut on the inner surface of the cap 3, the cap 3 is prevented from swinging with respect to the barrel 1. Also, on the outer peripheral surface of the front end portion of the barrel 1,
A male screw portion is formed, and a conical tip member 7 made of a transparent material and having a female screw formed on the inner surface is screwed to the male screw portion. A large number of V-grooves 8 are formed on the circumferential surface where the female screw portion of the tip member 7 is located, so that the screw portion at the tip of the barrel 1 and the female screw portion of the tip member 7 can be seen through. To prevent them from getting lost. That is, the light is diffusely reflected by the V-grooves 8, making the interior difficult to see, and improving the aesthetic appearance.

Further, at the intermediate portion of the conical tip member 7,
A step 9 is formed, and the cap 3 is
Of the inner stage 10 can come into contact with each other. While preventing the cap 3 from being excessively immersed in the barrel 1 when inserted in front of the cap 3 barrel 1,
It also prevents run-out when the cap is placed.

The front end of the core tank 2 has a reduced diameter portion 11.
The inside of the reduced diameter portion 11 has a core
A chuck body 12 for releasing is fixed, and a chuck ring 13 is fitted around the front outer periphery of the chuck body 12. The chuck ring 13 closes and expands the chuck body 12. A center detent member 14 for preventing the retracted core from being retracted is integrally formed with the tip member 7 in front of the chuck body 12 and inside the tip member 7, but as a separate member such as a rubber-like elastic body. It may be formed and fixed to the tip member 7. Reference numeral 15 denotes a chuck body 13 fixed to the front end of the core tank 2 for urging the chuck body 12 rearward.
2 is a chuck spring for closing the core 2 and holding the core.

On the other hand, the large diameter portion 16
Are formed integrally, and inside the large diameter portion 16,
A receiving step 18 to which the eraser 17 is detachably attached is formed. A fitting recess 19 is formed below the outer periphery of the large-diameter portion 16 so as to fit with the inner rib 4 of the cap 3. That is, the inner rib 4 of the cap 3 can be fitted to the fitting recess 19 of the core tank 2 and also to the fitting recess 5 in front of the barrel 1. A knock cap 20 that covers the eraser 17 is removably fitted above the outer periphery of the large diameter portion 16 of the core tank 2,
The periphery of the top surface of the knock cap 20 is rounded (rounded portion 21). When the cap 3 is inserted into the large-diameter portion 16 of the core tank 2, the cap 3 is prevented from being damaged by contact between the inner surface of the cap 3 and the edge of the knock cap 20, and is made to be easily inserted. is there.

The front of the cap 3 is formed to extend so as to cover the rear part of the barrel 1. The inner diameter of the cap 3 in the covered portion is substantially the same as the outer diameter of the barrel 1, but has a slight gap because they slide with each other. Specifically, it has a gap of about 0.1 mm. Further, the inner diameter at the rear of the cap 3 is substantially the same as the outer diameter at the rear of the knock cap 20, but is set so as not to be press-fitted. The fitting of the cap 3 to the knock cap 20 and the
The extension of the front portion of the cap to the rear portion of the barrel 1 and the rear inner diameter of the cap 3 and the rear outer diameter of the knock cap are made substantially the same to minimize the deflection of the cap when the cap is pressed. Preventing. In addition, a locking rib 3b that can abut on the top of the knock cap 20 is formed inside the cap 3 to prevent the knock cap 20 from being excessively immersed. When not in use, the cap 3 is detached from the large diameter portion 16 of the core tank 2,
The fitting is made into the fitting recess 5 below (front) of the barrel 1 (FIG. 7).
reference). The mounting of the cap 3 protects the tip of the tip member 7 and prevents the core from being unnecessarily extended even if unexpected centering is performed. That is, when the lead is extended, the tip of the lead comes into contact with the inner bottom surface 3a of the cap 3 and the advance (forward movement) of the lead is prevented. In addition, the advance of the lead is prevented by an appropriate amount of extension (length with the lead), so that there is also an effect that the lead-out operation of the lead to be used is not required. Incidentally, in this example, since the distance from the tip of the tip member 7 to the inner surface bottom 3a is about 1.5 mm, even if the lead is accidentally extended, the protrusion of the lead is 1.5 mm. .
When writing, it is a suitable protrusion amount.

In the side wall of the center portion of the core tank 2, through holes 22 are formed at two opposing positions (a total of four positions), but may be at three or five positions. By forming the through hole 22 in the side wall of the core tank 2,
Charging of the core tank 2 is prevented, and adhesion of the core to the inner surface of the core tank 2 is prevented. When a charging agent is applied to the inner surface of the core tank 2, drying of the charging agent can be promoted, and productivity can be improved. Further, in the case where the core tank is formed by injection molding or the like and the above-described through hole is formed, a pin member that comes into contact with a core pin forming a hollow portion of the core tank from a direction perpendicular to the core tank is required. The effect that bending is prevented and uneven thickness and bending of the lead tank are prevented is also produced.

Reference numeral 23 denotes a pointed gate mark generated when the lead tank 2 is formed by injection molding. The gate 23 is formed at the position of the concave portion 24 so as not to protrude from the surface of the core tank 2. However, depending on whether the gate 23 is generated, the gate 23 may be formed longer, and the longer gate may be formed. In some cases, sliding damage may occur on the inner surface of the barrel 1 due to the gap 23. In addition, although the concave portion 24 is formed to prevent sliding scratches, burrs may be generated around the concave portion 24, and the burrs may cause sliding scratches. Therefore, in this example, as a means for preventing these scratches, the gate 23 (the concave portion 2) is used.
Around the 4), projections 25 whose tops are arc-shaped are formed at four places.

As the transparent material of the barrel 1 and the core tank, PET (polyethylene terephthalate), transparent polyamide, PC (polycarbonate), ABS (acrylonitrile / butadiene / styrene copolymer), AS ( Acrylonitrile / styrene copolymer resin), PP (polypropylene) and the like. Transparency, strength of the fixing portion of the chuck body to the core tank and the screwing portion of the tip member to the shaft cylinder, and the like, Considering the hygroscopicity for preventing the electrostatic attraction of the core to the inner surface of the core tank, PET and a transparent polyamide, and a copolyester of PCT and PET containing a large amount of a PCT (polycyclohexylene terephthalate) component are used. Since the alloy with PC has good fluidity of the resin at the time of molding and also has good stability of strength over time,
It can be said that it is a particularly preferable material.

Here, the sectional shape of the barrel 1 and the core tank 2 may be circular, but may be polygonal in order to make the core more visible. The lens effect allows the core to appear thicker and more transparent, as well as more easily confirmed. In this example, the cross section of the barrel 1 is circular, but the cross section of the core tank 2 is hexagonal. In addition, the hexagonal core tank 2 is formed with a roundness 2a at a corner thereof to further enhance the presence or absence of the lens effect. Also, by forming roundness 2a at the corners of the core tank 2, the hexagonal inner wall surface 2b allows the chuck press-fit holes 2c to be formed.
Distance (difference in inner diameter) can be increased,
The surface area of the step 2d can be increased. As a result,
The contact area between the jig used to assemble and press-fit the chuck body 12 into the core tank 2 and the jig inserted inside the core tank 2 and the stepped portion 2d can be increased, and thus the core formed by press-fitting the core can be obtained. The whitening and cracking of the tank 2 are prevented. Incidentally, the dot part shown in FIG. 7 is the surface area of the step part 2d of the present invention, and the dot part shown in FIG. 8 is the step part 2d when the roundness 2a is not formed at the corner of the core tank 2.
Is the surface area of

A second example will be described with reference to FIGS. A tip member 7 and a knock cap 20 are provided on the inner surface of the cap 3.
This is an example in which an elastic piece 26 that can abut the elastic member 26 is formed. When caps are attached to each (tip member side, knock cap side)
Deflection of the cap 3 with respect to the barrel 1 is further prevented.

A third example will be described with reference to FIG. The knock cap 27 is not fitted to the core tank 2 but is detachably fitted to the barrel 1. That is, depending on the pressing operation of the knock cap 27, the operation of extending the lead cannot be performed. A slit 28 formed from the top is provided on the side surface of the knock cap 27.
Are formed radially. On the other hand, a pressing rib 29 is formed inside the cap 3 so as to be inserted into the slit 28 and to come into contact with the rear end of the core tank 2 (the rear end of the large diameter portion 16). Unless the cap 3 is inserted into the knock cap 27 side, the core can not be extended. Since the slit 28 also serves as an air exchange path connecting the inside and the outside of the knock cap 27,
Even if a child swallows knock cap 27, suffocation death for a certain period of time can be prevented.

[0016]

According to the present invention, there is provided a mechanical pencil having a lead tank protruding from the rear end of the barrel. The mechanical pencil has detachable caps at the front of the barrel and at the rear of the lead tank. When the cap is attached to the core tank, the front end of the cap is formed to extend to a position covering the rear part of the barrel, so that the cap is operated at the time of pressing operation (core feeding operation). The deflection of the cap can be prevented as much as possible.

[Brief description of the drawings]

FIG. 1 is a longitudinal half sectional view of the present invention (when a cap is fitted to the front: the cap is a longitudinal sectional view).

FIG. 2 is an enlarged longitudinal sectional view of a lower (front) portion of FIG.

FIG. 3 is an enlarged view of a portion A in FIG. 2;

FIG. 4 is a longitudinal half sectional view of the present invention (when the cap is fitted to the rear: the cap is a longitudinal sectional view).

FIG. 5 is an enlarged external view of a main part of a core tank.

FIG. 6 is a sectional view taken along line BB of FIG. 5;

FIG. 7 is a sectional view taken along line CC of FIG. 2;

FIG. 8 is a cross-sectional view of a main part when the core tank is not rounded, corresponding to FIG. 7;

FIG. 9 is a longitudinal half sectional view of a main part showing a second example (when the cap is fitted to the front: the cap is a longitudinal sectional view).

FIG. 10 is a longitudinal half sectional view of a main part showing a second example (when the cap is fitted to the rear: the cap is a longitudinal sectional view).

FIG. 11 is a sectional view taken along line DD of FIG. 10;

FIG. 12 is a vertical sectional view of a main part showing a third example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft cylinder 2 core tank 3 Cap 4 Inner rib 5 Fitting concave portion 6 Projection 7 Tip member 8 V groove 9 Step 10 Inner surface engaging portion 11 Reduced diameter portion 12 Chuck body 13 Chucking 14 Core detent member 15 Chuck spring 16 Large diameter portion 17 Eraser 18 Receiving step portion 19 Fitting concave portion 20 Knock cap 21 Round portion 22 Through hole 23 Gate mark 24 Recess 25 Projection 26 Elastic piece 27 Knock cap 28 Slit 29 Press rib

Claims (2)

[Claims] 1. A mechanical pencil having a lead tank protruding from a rear end of a barrel, the mechanical pencil having detachable caps at the front of the barrel and at the rear of the lead tank. The cap-type mechanical pencil, wherein when the cap is mounted on the lead tank, a front end of the cap is formed to extend to a position covering a rear portion of the barrel. 2. The cap-type mechanical pencil according to claim 1, wherein a tip member is disposed in front of the barrel, and the tip member and the cap are inserted when the cap is inserted in front of the barrel. A cap-type mechanical pencil having immersion prevention means that locks at a fixed position.